Power and Energy

Recommended for High School.

Introduction

People often use the words power and energy interchangeably, when in fact these two words mean very different things.

Imagine if people used the words “kilometers per hour” and “kilometers” interchangeably. That would be very confusing! It might sound like this: “How fast can you ride your bike?” “About 5 kilometers.” This is basically what we are doing if we use power and energy to mean the same thing.

Power is a rate–just like meters per second, miles per hour, or gallons per minute are rates. Power is the rate at which work is done and can be calculated using the equation

The base unit of power is the watt (W), which is equal to one joule per second (1 W = 1 J/s).

We can think of energy, on the other hand, as a quantity–just like gallons or meters are quantities. Energy refers to the quantity of work performed. The base unit of energy is the joule (J). If you know power and length of time, you can calculate energy by rearranging the power expression in the following way:

In this experiment, you will explore power and energy. You will learn how power and energy are related to each other. You will use this knowledge and the data-collection software to measure the power and calculate the amount of electrical energy generated by a small wind turbine.

Objectives

Understand the difference between power and energy and the common units used for each.

Calculate the amount of electrical energy generated by a wind turbine over time.